This invention relates to new and useful improvements in sample procedure preparations for the analysis of pesticides, toxic chemicals and drugs using micro techniques of column chromatographic cleanup and concentration as a one-step procedure. All previous methods required individual sample handling at the cleanup stage and individual concentration prior to gas liquid chromatography.
In toxicological studies of pesticides, for example, there is often a need to analyze large numbers of small tissue samples. Although rapid methods of extraction of small samples have been developed, the cleanup and concentration of the extract for gas chromatographic analysis is somewhat time consuming. Furthermore, the recommended multiresidue procedure for cleanup of extracts containing insecticides, other toxic chemicals and pollutants use relatively large quantities of chromatographic materials and solvents as well as requiring separate evaporation of the eluant and transfer to a test tube for gas chromatographic analysis.
There has been developed an apparatus for the micro cleanup and concentration of trace residue analysis by gas liquid chromatography and such apparatus is described in an article by the applicant and published in Analytical Chemistry Volume 51, page 1861, September 1979.
In the apparatus described therein, a glass filament concentrator is shown consisting of a cylindrical glass jacket and a glass filament therein. The glass filament is hand drawn from solid glass tubing and terminates in a one millimeter diameter glass filament of some thirty centimeters in length.
This filament is concentric with the inner wall of the jacket and not only is extremely difficult to produce commercially, but suffers from several disadvantages. Firstly, it vibrates due to inherent ambient vibration and occasionally a concentrated drop is lost on the joint resulting in large false lower readings. Breakage also occurs readily during transportation, handling and storage of such apparatus. Furthermore, if a last drop of liquid gathers at the lower tip of the filament, it tends to evaporate as the weight thereof is often not sufficient to enable it to drop and be collected. This also causes additional losses and hence false readings to the end result.